Flannan Isles Lighthouse
Just before Christmas in 1900, Flannan Isles had three lighthouse keepers. Then there were none. The men disappeared without a trace and were never heard from again. Additionally, there was zero proof of anything that might have occurred. Nothing suggested a solution, whether they had quit their jobs, drowned, or were murdered.
People are still looking for answers to the mystery of what happened more than 100 years later. One explanation for the incident is that nature triumphed over the men. Two of the lighthouse keepers received citations for storing equipment inappropriately. To make sure everything was safe, they might have left in a storm. The males might have been carried away by a wave that struck.
Of course, that is only a theory, though it is conceivable. The issue is that it will always be a theory because there are no corpses. There have been rumors that the scene had a toppled chair and a half-eaten lunch, which may have been a sign of foul play. However, those rumors started to spread a few years later.